Less than year you're good with a Canadian license. Longer than a year you're supposed to get a state license but I'm not sure how often this is actually enforced.

From my understanding you do need to retake the tests but the US driving tests are genuinely quite easy and would probably take part of an afternoon for an experienced driver.

Legally you can lease a car with an international license. Your works HR might be able to help you with some of this relocation info.

You can also always contact the DMV make sure you're getting correct info https://www.dmv.pa.gov/pages/Contact-Us.aspx